Noun
side issue (plural side issues)
(idiomatic) An issue or topic which is not of direct significance to a primary concern.
Moreover, behind this vague tendency to treat religion as a side issue in modern life, there exists a strong body of opinion that is actively hostile to Christianity and that regards the destruction of positive religion as absolutely necessary to the advance of modern culture. Christopher Dawson
The fate of farm animals is not an ethical side issue. It concerns the majority of Earth's large creatures: tens of billions of sentient beings, each with a complex world of sensations and emotions, but who live and die as cogs in an industrial production line. Yuval Noah Harari
This became a political side issue, as FNLA and UNITA, given their regional constituencies, came out in favour of a greater attention to the African languages, and as the FNLA favoured French over Portuguese. Source: Internet
It's a side issue. Source: Internet